|Thomas, W t b|
Submitted to: Journal of Experimental Botany
Publication Type: Peer reviewed journal
Publication Acceptance Date: 9/15/2000
Publication Date: N/A
Citation: Interpretive Summary: Wild barley is the progenitor of cultivated barley and is widely distributed in the Fertile Crescent of the Near East (e.g., Israel, Jordan, Syria, Turkey) where domestication took place some 10,000 years ago. Barley is an established model species for genetics and physiology, due partly to its simple genetics and annual life cycle, but also to its importance as a world crop. The variation found in wild barley is of interest to geneticists, physiologists, plant breeders and ecologists. A wild barley population from Tabigha, a micro-site north of the Sea of Galilee, Israel, has been analysed in several studies. The Tabigha site is of particular ecological interest as the barley population there spans two diverse soil types, Terra Rossa soil (TR) and Basalt derived soil (B). The TR and B soils vary markedly in their water holding capacity, with the B soil having a greater capacity at retaining moisture. This combined with the relatively low annual rainfall (2 inches) and almost no rain in early summer results in severe drought primarily in TR. An experiment was designed to mimic the natural early summer drought (imposed water stress = drought), to measure responses to water stress, to compare these with non-stressed plants, and relate the results to adaptation to soil type. Plant response to imposed water stress differed between B and TR sites. Those in TR were most tolerant to drought, and thus plants were identified which could be used by plant breeders to incorporate resistance to drought stress in commercial cultivars, which could decrease grower losses during drought conditions.
Technical Abstract: A study was conducted to investigate responses to water stress within a population of wild barley from Tabigha, Israel. The Tabigha population spans two distinct soil types: Terra Rossa and Basalt. Seeds were collected from plants along a 100m transect; 24 genotypes were sampled from Terra Rossa soil (TR) and 28 from the Basalt soil (B). Due to different water holding capacities of the two soils, plants growing on TR naturally experience more intense drought than plants growing on B. In a glasshouse experiment, water was withheld from plants starting at the flag leaf stage for two periods lasting 10 and 14 days. A total of 15 agronomic, morphological, developmental and fertility related traits were recorded and subjected to analysis of variance (ANOVA). A high degree of phenotypic variation was found in the population with significant genotype x treatment and soiltype x treatment interactions. Principal component analysis (PCA) was performed using combined control and stress treatment data sets. The relative performance of individual genotypes was compared by PCA and water stress tolerant genotypes identified. With respect to yield traits, TR genotypes were significantly less affected by the imposed water stress than B genotypes. Moreover, TR genotypes showed accelerated development under water deficit conditions. Genotypes possessing specific responses may be exploited in comparative physiological studies and TR genotypes exhibiting yield stability may be of value in breeding barley better adapted to drought.